Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$195.81	5.163%	$205.9197	$205.92	$205.90	$205.90
Purchase #2	$207.60	9.531%	$227.3864	$227.39	$227.40	$227.40
Purchase #3	$211.78	6.214%	$224.94	$224.94	$224.95	$224.90
Purchase #4	$10.52	12.695%	$11.8555	$11.86	$11.85	$11.90
Purchase #5	$58.47	11.389%	$65.1291	$65.13	$65.15	$65.10
Purchase #6	$29.82	5.647%	$31.5039	$31.50	$31.50	$31.50
Purchase #7	$53.79	10.612%	$59.4982	$59.50	$59.50	$59.50
7 purchase totals =	$767.79		$826.2328	$826.24	$826.25	$826.20